for an example, see http://ircalc.usps.gov/details.asp?txtMaxIndemnity=2020&txtIndemnity=500&RadioReturn=1.75&Method=20&Cost=16&Commit=4+-+10+Days&MethodText=Airmail+Parcel+Post&Country=Great+Britain+and+Northern+Ireland&Pounds=1&Ounces=0&Oversize=&GXGNonWeight=Max.length+60"%2C+max.+length+plus+girth+108"&bCOM=True&bPickup=True&bReturnReceipt=False&RadioSS=2&cmdSubmit=Continue

That's a 1 pound package with $500 insurance and a return receipt for $25.

Another example is http://ircalc.usps.gov/details.asp?txtMaxIndemnity=40.45&RadioCOM=0&Method=16&Cost=6.4&Commit=4+-+7+Days&MethodText=Airmail+Letter+Post&Country=Great+Britain+and+Northern+Ireland&Pounds=0&Ounces=8&Oversize=&GXGNonWeight=Max.+length+24"%2C+Max.+length%2C+height%2C+depth+combined+36"&bCOM=True&bPickup=False&bReturnReceipt=False&RadioSS=0&cmdSubmit=Continue

That's an 8 ounce padded envelope with no special insurance or handling for $6.40

all rates can be found at http://ircalc.usps.gov/